Getopt::Std(3)

NAME
     getopt - Process single-character switches with switch clustering

     getopts - Process single-character switches with switch clustering

SYNOPSIS
         use Getopt::Std;

         getopt('oDI');    # -o, -D & -I take arg.  Sets opt_* as a side effect.
         getopt('oDI', \%opts);    # -o, -D & -I take arg.  Values in %opts
         getopts('oif:');  # -o & -i are boolean flags, -f takes an argument
                           # Sets opt_* as a side effect.
         getopts('oif:', \%opts);  # options as above. Values in %opts


DESCRIPTION
     The getopt() functions processes single-character switches with switch
     clustering.  Pass one argument which is a string containing all switches
     that take an argument.  For each switch found, sets $opt_x (where x is
     the switch name) to the value of the argument, or 1 if no argument.
     Switches which take an argument don't care whether there is a space
     between the switch and the argument.

     Note that, if your code is running under the recommended use strict
     'vars' pragma, it may be helpful to declare these package variables via
     use vars perhaps something like this:

         use vars qw/ $opt_foo $opt_bar /;

     For those of you who don't like additional variables being created,
     getopt() and getopts() will also accept a hash reference as an optional
     second argument. Hash keys will be x (where x is the switch name) with
     key values the value of the argument or 1 if no argument is specified.